There is being developed a VUV light (a vacuum ultraviolet light) processing apparatus that applies VUV (Vacuum Ultra-Violet) light to a sample such as a semiconductor device substrate (a wafer) or the like for processing.
A conventional VUV light (vacuum ultraviolet light) processing apparatus using an excimer lamp or the like at a wavelength of 200 nm or less generally processes a wafer as described in Patent Document 1, for example, in which a plurality of tubular excimer lamps are provided and vacuum ultraviolet light is applied to a wafer, which is a sample to be processed, for processing.
In such a conventional VUV light (vacuum ultraviolet light) processing apparatus using excimer lamps, cylindrical excimer lamps using dielectric barrier discharge at a wavelength of 200 nm or less, for example, are disposed in a lamp house. For the cylindrical excimer lamp, a Xe excimer lamp that emits excimer light at a wavelength of 172 nm is often used. In a processing chamber, a wafer in a diameter of 300 mm, for example, which is a sample to be processed, is placed on a wafer stage. Moreover, a window that can transmit vacuum ultraviolet light is disposed between the lamp house and the processing chamber in such a way that vacuum ultraviolet light emitted from the cylindrical excimer lamp is applied to the wafer. In this case, for a window material, a flat plate made of synthetic silica that can transmit excimer light at a wavelength of 172 nm, for example is used. The lamp house and the processing chamber are partitioned from each other by the window.
A gas inlet port and a gas outlet port are provided in the lamp house. In this case, N2 gas is introduced, and the inside of the lamp house is substituted with N2, thereby suppressing the attenuation of vacuum ultraviolet light due to O2 in the air. At the same time, N2 gas is introduced to cool the cylindrical excimer lamps and the window for mitigating a reduction in the light intensity of vacuum ultraviolet light in association with a shift of the transmission limit of vacuum ultraviolet light caused by a temperature rise of synthetic silica. Similarly, a gas inlet port and a gas outlet port are also provided in the processing chamber. In this case, N2 gas is introduced, and the inside of the processing chamber is substituted with N2, thereby suppressing the attenuation of vacuum ultraviolet light due to O2 in the air.
Moreover, in another example, a vacuum outlet port provided on a processing chamber and a vacuum exhaust system are used to evacuate the inside of the processing chamber, and vacuum ultraviolet light is applied to a wafer. In still another example, a vacuum outlet port and a gas inlet port provided on a processing chamber, a vacuum exhaust system, and a gas supply system are used to evacuate the inside of the processing chamber, a gas is introduced into the processing chamber, and, under reduced pressure, vacuum ultraviolet light is applied to a wafer.
For the applications of the VUV (Vacuum Ultraviolet light) processing apparatus, there are low-k curing, post lithography (a reduction in resist LWR after lithography, that is, VUV curing) and so on. Among them, for techniques related to a reduction in resist LWR, there is plasma processing using HBr plasma, N2 plasma, or the like as in Patent Document 2, that is, a reduction in resist LWR by plasma curing.
A technique that forms fine patterns is necessary to increase the integration degree of semiconductor integrated circuits. Generally, in the semiconductor manufacturing processes, photolithography techniques are used.
In the photolithography techniques, first, a photoresist material is coated on a thin film laminate on a semiconductor substrate, and ultraviolet light or the like is applied using an exposure apparatus. Thus, circuit patterns formed on a photomask are transferred to the resist material, and the transferred resist material is further developed.
A plasma processing apparatus is generally used for the process of transferring the circuit patterns of the developed photoresist to under layers of laminate thin films. The plasma processing apparatus usually includes a vacuum chamber, an exhaust system that keeps the pressure inside a processing chamber formed in the vacuum chamber to a predetermined pressure, a plasma gas supply system, a wafer mounting electrode that places and fixes a wafer thereon, and an upper electrode including an antenna to generate plasma. A process gas is introduced into the processing chamber, and glow discharge is generated in the introduced process gas (mixed gas), thereby generating plasma. The generated plasma is used to generate highly reactive radicals and ions for etching.
For a method of forming a fine gate electrode by etching, Patent Document 3, for example, describes that an insulating film, a conductive layer, and an organic material layer are formed on a semiconductor substrate, a first mask pattern in a mask dimension β is formed on the organic material layer using the photolithography techniques, the organic material layer is etched using a mixed gas of Cl2 and O2, the first mask pattern is shrunk to form a second mask pattern in a mask dimension Y (<β), the conductive layer is etched using the second mask pattern, and then a gate electrode in dimensions smaller than the mask dimension β is obtained.
Furthermore, for methods of improving the etch resistance of a resist, there is described a process in which an electron beam is applied to cure a photoresist (see Patent Document 4), or a process in which vacuum ultraviolet light at a wavelength of 200 nm or less is applied to a resist pattern obtained by development for curing (see Patent Document 5).